There is a problem when following instructions in Documentation > Installation > Sample Data for importing the xml file. I am importing the XML document from folder All. When submitting the Import action, the import fails at some consecutive file image onward. The error does not list any additional information, just that the file failed to import. I am looking at my S3 storage and files do get uploaded, but not the one that failed to import. Now the problem probably arises because I am using the plugin Amazon S3 and Cloudfront. I did manage to get past this by triggering upload multiple times, it took approximately 7 upload tries and every time more and more files were imported into the S3 storage. In the end I managed to import them all. If I were to take a guess what the source of the problem is, I would say it has to do something with timing out when importing because for each file saved to server, the plugin saves it to AWS S3 storage and deletes it on local storage. Though I am not sure if this in the end has anything to do with your template, but more with WordPress Importer plugin.